Testing device and method for checking the operability of a nose wheel steering control unit in an aircraft

ABSTRACT

The invention relates to a testing device ( 12 ) for checking the operability of a bow steer control unit ( 10 ) in an aircraft. The bow steer control unit has a plurality of input ports and a plurality of output ports, wherein at least one of the input ports of the bow steer control unit is connectable to a speed sensor, which provides a signal representing the actual speed of the bow wheel of the aircraft. The bow steer control unit outputs a blocking signal to be transmitted to a steering mechanism as soon as the detected actual speed of the bow wheel exceeds a predetermined bow wheel speed value. The testing device comprises a connection interface ( 14 ) to be connected to at least one input port of the bow steer control unit and a bow wheel speed simulating nit for generating a bow wheel speed simulation signal, which represents a particular simulated bow wheel speed value exceeding the predetermined speed value The generated bow wheel speed simulation signal is transmitted to the bow steer control unit via the connection interface. The output of the bow steer control unit in response to the received bow wheel speed simulation signal is then monitored.

The present invention relates to a testing device and a correspondingmethod for checking the operability of a bow steer control unit in anaircraft.

In the field of aircraft, it is necessary to block the steering functionof a front steering wheel arranged at the bow of the aircraft as soon asthe aircraft runs on the ground with a certain velocity, e.g. above 70knots. This means that the bow wheel (i.e. the front wheel) of therespective aircraft must be blocked against any steering movement, evenif a respective signal from the cockpit is received by the steeringmechanism. The control of the bow wheel steering is performed by a bowsteer control unit. For safety reasons, modern aircrafts usuallycomprise two separate bow steer control units which are usuallyaccommodated within common single housing. Both bow steer control unitsare adapted to control the steering of the bow wheel as well as tomonitor the operation of the bow wheel steering. It is also known in theart to use both bow steer control units, synchronously, wherein one bowsteer unit is in a command mode controlling the bow steering and therespective other bow steer control unit is in a monitoring modemonitoring the operation of the bow steering. After each flight, thecommand and monitoring responsibility of the two bow steer control unitsare changed, i.e. both bow steer control units are used alternately formonitoring and controlling.

It is also common practice to use a plurality of speed sensors in orderto monitor the actual speed of the bow wheel. Each speed sensor, or atleast a plurality of the bow wheel speed sensors, provided in theaircraft are connected to the bow steer control unit and transmit outputsignals thereto. Moreover, the bow steer control unit can also beconnected to a plurality of further components of the aircraft, forexample for controlling the ground spoiler, for controlling the slatsand the aileron and for outputting certain operational states by opticalindicators or the like.

In order to guarantee a high fail safety, the operability of the bowsteer control units are to be checked in regular intervals. It is theobject of the present invention to provide a testing device and acorresponding method for checking the operability of a bow steer controlunit in an aircraft in an easy and time saving manner.

This object is solved by a testing device for checking the operabilityof a bow steer control unit in an aircraft, wherein the bow steercontrol unit has a plurality of input ports and a plurality of outputports, wherein at least one of the input ports of the bow steer controlunit is connectable to a speed sensor, which provides a signalrepresenting the actual speed of the bow wheel of the aircraft, andwherein the bow steer control unit outputs a blocking signal to betransmitted to a steering mechanism as soon as the detected actual speedof the bow wheel exceeds a predetermined bow wheel speed value. Thetesting device comprises a connection interface to be connected to atleast one input port of the bow steer control unit and a bow wheel speedsimulating unit for generating a bow wheel speed simulation signal,which represents a particular simulated bow wheel speed value exceedingthe predetermined speed value, wherein the generated bow wheel speedsimulation signal is transmitted to the bow steer control unit via theconnection interface and wherein the output of the bow steer controlunit in response to the received bow wheel speed simulation signal ismonitored.

The testing device can be easily connected to the bow steer control unitby connecting the connection interface of the testing device to therespective input and output ports of the bow steer control unit.Preferably, respective plug connectors are provided. Thereafter, certaintest procedures can be performed manually or automatically by using thetesting device.

It may be necessary to dismount from the bow steer control unit theaircraft in order to connect the connection interface of the testingdevice according to the invention to the respective input and outputports of the bow steer control unit, e.g. via the plug connectors.

According to one embodiment of the invention, the bow steer control unitcomprises a plurality of speed sensor input ports each connectable to aseparate speed sensor and wherein the connection interface comprisescorresponding simulated speed signal output ports to be connected to thespeed sensor input ports of the bow steer control unit. Thereby, thefunction of all speed sensors and the interaction between these speedsensors and the bow steer control unit can be tested. It is possible tocheck the interaction between the bow steer control unit and each of thespeed sensors, separately, by deactivating the connection between allspeed sensors and the bow steer control unit and by sending a simulatedspeed sensor signal from the testing device to the bow steer controlunit. The reaction of the bow steer control unit in response to thereceived simulated speed sensor signal is then monitored.

The bow steer control unit according to the invention may comprise atleast one, preferably two, bow wheel speed simulation signal generatorsfor generating an AC voltage signal, in particular in a frequency rangearound 2600 Hz. Such an AC voltage signal usually corresponds to avelocity of 90 knots. Usually, the predetermined bow wheel speed value,which is relevant for blocking the steering function of the bow wheel,is in the range of 70 knots. By using of two bow wheel speed simulationsignal generators, which are preferably sinus generators, the failsafety of the testing device according to the invention can be improved.

In order to facilitate the use of the testing device according to theinvention, the connection interface may further include a voltage supplyport to be connected to a voltage output of the bow steer control unit.Thereby, there is no additional, i.e. external, voltage supplynecessary.

In a further embodiment, the testing device may comprise a supplyindicator, in particular an optical supply indicator, for indicating anappropriate voltage supply. Moreover, it is possible according to theinvention that the testing device further comprises a manual userinterface for a manual activation of testing functions of the testingdevice. Thus, as already indicated above, it is possible to performpredetermined testing procedures automatically or to check theoperability of the bow steer control unit and further components of theaircraft connected thereto manually.

As already discussed in the introductory part, usually airports providesimulation systems for the aircrafts. Considering this, according to oneembodiment of the invention the connection interface includes connectionports to be connected to an external simulation system, in particular toan airport operation system, providing predetermined simulationprocedures based on airport related parameters for simulating certainoperation scenarios.

According to a further embodiment of the invention the connectioninterface further comprises at least one input port to be connected to acorresponding output port of the bow steer control unit for checking thecorrectness of the output signal provided by the bow steer control unitin response to the bow wheel speed simulation signal. This output caninclude an optical or acoustical indication.

According to a further embodiment of the invention, the connectioninterface further comprises at least one output port to be connected toa further external component interacting with the bow steer control unitwherein the bow steer control unit provides a simulated output signalfor checking the operability of external component.

This function is may be required, as a plurality of external componentsin the aircraft are fed with signals from the bow steer control unit andcontrolled based thereupon.

One example for such an external component is the ground spoiler controlunit. Thus, according to one embodiment of the invention of the outputports of the connection interface is adapted to be connected to a groundspoiler control unit for checking whether the ground spoiler controlunit drives a ground spoiler, when the received signal indicates thatthe bow wheel speed has exceeded the predetermined speed value.Considering this, it is possible according to the invention that theconnection interface includes an output port for the left wing groundspoiler control unit and a further output port for the right wing groundspoiler control unit, respectively.

In addition or as an alternative to a connection to the ground spoilercontrol unit, it is also possible according to the invention, that oneof the output ports of the connection interface is adapted to beconnected to an aircraft data monitoring device for checking whether theaircraft data monitoring device processes and indicates the receivedsimulated data, appropriately.

Moreover, it is possible that one of the output ports of the connectioninterface is adapted to be connected to slat aileron control device forchecking whether the slat aileron control device controls the slatsand/or the aileron appropriately after the predetermined speed value hasbeen exceeded by the bow wheel speed simulation signal. Consideringthis, it is also possible that the connection interface includes twosets of output ports, each separately connectable to one of two separateslat aileron control devices provided in the aircraft, wherein thetesting device is arranged to operate the two separate slat aileroncontrol devices, synchronously, such that one of the slat aileroncontrol devices operates in an activated command mode, when therespective other slat aileron control device operates in a monitoringmode.

As already indicated in the introductory part, it is common practice toprovide an aircraft with two separate bow steer control units.Considering this measure for increasing the fail safety, a furtherembodiment according to the present invention provides that theconnection interface includes two sets of output ports each separatelyconnectable to one of two separate bow steer control units provided inthe aircraft, wherein the testing device is adapted to operate and testthe two separate bow steer control units, synchronously, such that oneof the bow steer control units operates in an activated command mode,when the respective other bow steer control unit operates in anmonitoring mode, and vice versa.

The object of the present invention is also achieved by a method forchecking the operability of a bow steer control unit in an aircraft,wherein the bow steer control unit has a plurality of input ports and aplurality of output ports, wherein at least one of the input ports ofthe bow steer control unit is connectable to a speed sensor whichprovides a signal representing the actual speed of the bow wheel of theaircraft and wherein the bow steer control unit outputs a blockingsignal to be transmitted to a steering mechanism as soon as the detectedactual speed of the bow wheel exceeds a predetermined bow wheel speedvalue. The method comprises the steps of connecting a connectioninterface of a testing device, as described above, to at least one inputport of the bow steer control unit, generating a bow wheel speedsimulation signal, which represents a particular simulated bow wheelspeed value exceeding the predetermined speed value, transmitting thegenerated bow wheel speed simulation signal to the bow steer controlunit via the connection interface and monitoring the output of the bowsteer control unit in response to the received bow wheel speedsimulation signal.

Thus, by applying the method according to the invention, it can bechecked whether the bow wheel indeed is blocked, when the bow wheelspeed simulation signal exceeds the predetermined speed value.

The method according to the present invention may further comprise thesteps of connecting the testing device to an external simulation system,in particular an airport operation system, which provides predeterminedsimulation procedures, and simulating certain operation scenarios basedon the predetermined simulation procedures.

Moreover, the method according to the invention may further comprise thesteps of connecting the testing device to a corresponding output port ofthe bow steer control unit and checking the correctness of the outputsignal provided by the bow steer control unit in response to the bowwheel speed simulation signal.

As already discussed above in view of the testing device, the methodaccording to the invention may further comprise the steps of connectingthe testing device to a further external component controlled by the bowsteer control unit and providing a simulated output signal, which istransmitted to the external component, for checking the operability ofexternal component.

In addition or in alternative to that, the method according to theinvention may further comprise the steps of connecting the testingdevice to a ground spoiler control unit and checking whether the groundspoiler control unit activates a ground spoiler after the predeterminedspeed value has been exceeded by the bow wheel speed simulation signal.

Furthermore, the method according to the invention may comprise thesteps of connecting the testing device to an aircraft data monitoringdevice and checking whether the aircraft data monitoring deviceprocesses and indicates the received simulated data, appropriately.

According to a further embodiment, the method according to the inventionmay comprise the steps of connecting the testing device to a slataileron control device and checking whether the slat aileron controldevice controls the slats and the aileron appropriately, after thepredetermined speed value has been exceeded by the bow wheel speedsimulation signal. Additionally, the method according to the inventionmay further comprise the steps of connecting the testing device to twoseparate slat aileron control devices provided in the aircraft andoperating the two separate slat aileron control devices, synchronously,by using the testing device such that one of the slat aileron controldevices operates in an activated command mode, when the respective otherslat aileron control device operates in an monitoring mode, and viceversa.

Finally, as already indicated above, the method according to theinvention may comprise the steps of connecting the testing device to oneof two separate bow steer control units provided in the aircraft andoperating the two separate bow steer control units, synchronously, byusing the testing device such that one of the bow steer control unitsoperates in an activated command mode, when the respective other bowsteer control unit operates in an monitoring mode, and vice versa.

A preferred embodiment of a testing device according to the presentinvention will now be explained in more detail with reference to theaccompanying drawings, in which:

FIG. 1 shows a perspective schematic view of a testing device accordingto the invention connected to a bow steer control unit and

FIG. 2 shows a top plan view of an embodiment of the manual userinterface of the testing device according to the invention.

FIG. 1 shows a bow steer control unit 10 and a testing device 12according to the invention, which are connected to each other by meansof a connection cable arrangement 14. The connection cable arrangement14 includes two parts. A first part 16 is connected to the testingdevice and has a female plug connector 18. A second part 20 of theconnecting cable 14 is connected to the bow steer control unit 10 andincludes a corresponding male plug connector 22. The plug connectors 18and 22 include terminals associated to input and output ports of boththe bow steer control unit 10 and the testing device 12. It alsoincludes power supply terminals for supplying power voltage to thetesting device 12.

FIG. 2 shows a top plan view of the user interface of the testing device12. The user interface includes in its upper third eight buttons 24-1,24-2, 24-3, 24-4, 24-5, 24-6, 24-7 and 24-8. With these eight buttons itis possible to activate a simulation of one of eight speed sensorsprovided to detect the wheel speed of the bow steering wheel of anaircraft. For example by pressing button 24-1, the first speed sensorassociated to the bow steering wheel of the aircraft is simulatedwhereas the other seven speed sensors are not simulated and deactivated.Thus, it is possible to provide a simulateted output signal generated bythe testing device 12 and to transmit it via the cable 14 to the bowsteer control unit 10 in order to check the operability of the bow steercontrol unit 10, in particular the response to the generated simulatedspeed sensor output signal of the testing device 12.

The testing device 12 moreover includes in the middle part on the leftside of FIG. 2 optical indicators 26, 28, 30, 32, 34, 36. These opticalindicators 26, 28, 30, 32, 34, 36 are used for showing, whether certaincontrol units which are provided twice in the aircraft, are currentlyworking in a command mode or in a monitoring mode. The indicators 26 to36 particularly indicate which of the Slat Aileron Control Units (SEC)are currently working in a command mode or a monitoring mode. Thetesting device also simulates a signal (valet signal) for the FlightManagement Computers (FMGC). This is due to the fact that in order toimprove the fail safety, modern aircrafts usually comprise certaincontrol units twice. When the first control unit works in the commandmode, the second control unit having the same functions operates in themonitoring mode and monitors the operation of the control system. Aftereach flight, for example, the tasks are interchanged with each other andthe control unit having monitored the operation of the system thencommands the respective system and the control unit having commanded thesystem then monitors the system. Thus, there is a predetermined order ofoperation, which also has to be checked with the testing device. Thiscan be done by means of the indicators 28 to 36. By using the switches38, 40, certain control units can be activated or deactivated. Moreover,there is a further optical indicator 42 for indicating, whether thepower supply to the testing device is sufficient or not.

The testing device 12 is adapted to perform the testing functionautomatically by executing a predetermined routine, such that aoperating person simply has to monitor, whether the output signalsconfirm the correct functioning of the tested bow steer control unit ornot. However, the testing device 12 also provides two switches 44 and 46for checking the interaction between the bow steer control unit 10 and aground spoiler control unit manually. By activating switch 44 it ispossible to check whether the ground spoiler control unit correctlyresponds to a signal coming from the bow steer control unit, e.g. byactivating the ground spoiler on the left side. The same applies forswitch 46, which is provided for a manual activation of the groundspoiler control unit for controlling the ground spoiler on the rightside.

The two switches 48 and 50 have a similar function. They are associatedto an aircraft data monitoring device, e.g. a system data acquisitioncomputer (SDAC). This aircraft data monitoring device outputs a certainsignal, for example an optical signal, in the cockpit of the aircraft,as soon as the speed limit of 70 knots has been exceeded by the bowwheel of the aircraft. As soon as this predetermined bow wheel speedvalue has been exceeded, the bow steering is to be blocked in order toavoid an accident. For checking, whether the aircraft data monitoringdevice (SDAC) correctly recognizes an excess of this predetermined bowwheel speed value, one of the two switches 48 and 50 are to be switchedon. Thereupon, a corresponding simulated signal is generated by thetesting device 12 and transmitted to the aircraft data monitoringdevice. Thereupon it is checked, whether the aircraft data monitoringdevice reacts appropriately or not.

Summarizing the application and the use of the testing device 12, it isto be stated that it is easily connectable to the bow steer control unit10 and that it facilitates to check the operability of certain functionsdirectly implemented in the bow steer control unit 10 or initiatedthereby, for example by outputting certain control signals.

1. A testing device for checking the operability of a nose wheelsteering control unit in an aircraft, wherein the nose wheel steeringcontrol unit has a plurality of input ports and a plurality of outputports, wherein at least one of the input ports of the nose wheelsteering control unit is connectable to a speed sensor, which provides asignal representing the actual speed of the nose wheel of the aircraft,and wherein the nose wheel steering control unit outputs a blockingsignal to be transmitted to a steering mechanism as soon as the detectedactual speed of the nose wheel exceeds a predetermined nose wheel speedvalue, the testing device comprising: a connection interface to beconnected to at least one input port of the nose wheel steering controlunit and a nose wheel speed simulating unit for generating a nose wheelspeed simulation signal which represents a particular simulated nosewheel speed value exceeding the predetermined speed value, wherein thegenerated nose wheel speed simulation signal is transmitted to the nosewheel steering control unit via the connection interface and wherein theoutput of the nose wheel steering control unit in response to thereceived nose wheel speed simulation signal is monitored.
 2. The testingdevice according to claim 1, wherein the nose wheel steering controlunit comprises a plurality of speed sensor input ports each connectableto separate speed sensors and wherein the connection interface comprisescorresponding simulated speed signal output ports to be connected to thespeed sensor input ports of the nose wheel steering control unit.
 3. Thetesting device according to claim 1, further comprising at least one,preferably two, nose wheel speed simulation signal generators forgenerating an AC voltage signal, in particular in a frequency range ofaround 2600 Hz.
 4. The testing device according to claim 1, wherein theconnection interface includes a voltage supply port to be connected to avoltage output of the nose wheel steering control unit.
 5. The testingdevice according to claim 1, further comprising a supply indicator, inparticular an optical supply indicator, for indicating an appropriatevoltage supply.
 6. The testing device according to claim 1, furthercomprising a manual user interface for a manual activation of testingfunctions of the testing device.
 7. The testing device according toclaim 1, wherein the connection interface includes connection ports tobe connected to an external simulation system, in particular an airportoperation system, providing predetermined simulation procedures forsimulating certain operation scenarios.
 8. The testing device accordingto claim 1, wherein the connection interface further comprises at leastone input port to be connected to a corresponding output port of thenose wheel steering control unit for checking the correctness of theoutput signal provided by the nose wheel steering control unit inresponse to the nose wheel speed simulation signal.
 9. The testingdevice according to claim 1, wherein the connection interface furthercomprises at least one output port to be connected to a further externalcomponent controlled by the nose wheel steering control unit, whereinthe nose wheel steering control unit provides a simulated output signalfor checking the operability of external component.
 10. The testingdevice according to claim 9, wherein one of the output ports of theconnection interface is adapted to be connected to a ground spoilercontrol unit for checking whether the ground spoiler control unitactivates a ground spoiler after having exceeded the predetermined speedvalue.
 11. The testing device according to claim 9, wherein theconnection interface includes an output port for the left wing groundspoiler control unit and an output port for the right wing groundspoiler control unit, respectively.
 12. The testing device according toclaim 9, wherein one of the output ports of the connection interface isadapted to be connected to an aircraft data monitoring device forchecking whether the aircraft data monitoring device processes andindicates the received simulated data appropriately.
 13. The testingdevice according to claim 9, wherein one of the output ports of theconnection interface is adapted to be connected to slat aileron controldevice for checking whether the slat aileron control device controls theslats and the aileron appropriately, after the predetermined speed valuehas been exceeded by the nose wheel speed simulation signal.
 14. Thetesting device according to claim 13, wherein the connection interfaceincludes two sets of output ports, each separately connectable to one oftwo separate slat aileron control devices provided in the aircraft,wherein the testing device is arranged to operate the two separate slataileron control devices, synchronously, such that one of the slataileron control devices operates in an activated command mode, when therespective other slat aileron control devices operates in an monitoringmode.
 15. The testing device according to claim 1, wherein theconnection interface includes two sets of output ports each separatelyconnectable to one of two separate nose wheel steering control unitsprovided in the aircraft, wherein the testing device is adapted tooperate the two separate nose wheel steering control units,synchronously, such that one of the nose wheel steering control unitsoperates in an activated command mode, when the respective other nosewheel steering control unit operates in an monitoring mode.
 16. A methodfor checking the operability of a nose wheel steering control unit in anaircraft, wherein the nose wheel steering control unit has a pluralityof input ports and a plurality of output ports, wherein at least one ofthe input ports of the nose wheel steering control unit (10) isconnectable to a speed sensor which provides a signal representing theactual speed of the nose wheel of the aircraft and wherein the nosewheel steering control unit outputs a blocking signal to be transmittedto a steering mechanism as soon as the detected actual speed of the nosewheel exceeds a predetermined nose wheel speed value, the methodcomprising the steps of: connecting a connection interface of a testingdevice according to one of the preceding claims to at least one inputport of the nose wheel steering control unit, generating a nose wheelspeed simulation signal which represents a particular simulated nosewheel speed value exceeding the predetermined speed value, transmittingthe generated nose wheel speed simulation signal to the nose wheelsteering control unit via the connection interface and monitoring theoutput of the nose wheel steering control unit in response to thereceived nose wheel speed simulation signal.
 17. The method according toclaim 16, further comprising the steps of connecting the testing deviceto an external simulation system, in particular an airport operationsystem, which provides predetermined simulation procedures, andsimulating certain operation scenarios based on the predeterminedsimulation procedures.
 18. The method according to claim 16, furthercomprising the steps of connecting the testing device to a correspondingoutput port of the nose wheel steering control unit and checking thecorrectness of the output signal provided by the nose wheel steeringcontrol unit in response to the nose wheel speed simulation signal. 19.The method according to claim 16, further comprising the steps ofconnecting the testing device to a further external component controlledby the nose wheel steering control unit and providing a simulated outputsignal, which is transmitted to the external component, for checking theoperability of external component.
 20. The method according to claim 16,further comprising the steps of connecting the testing device to aground spoiler control unit and checking whether the ground spoilercontrol unit activates a ground spoiler after the predetermined speedvalue has been exceeded by the nose wheel speed simulation signal. 21.The method according to claim 16, further comprising the steps ofconnecting the testing device to an aircraft data monitoring device andchecking whether the aircraft data monitoring device processes andindicates the received simulated data appropriately.
 22. The methodaccording to claim 16, further comprising the steps of connecting thetesting device to a slat aileron control device and checking whether theslat aileron control device controls the slats and the aileronappropriately after the predetermined speed value has been exceeded bythe nose wheel speed simulation signal.
 23. The method according toclaim 22, further comprising the steps of connecting the testing deviceto two separate slat aileron control devices provided in the aircraftand operating the two separate slat aileron control devices,synchronously, by using the testing device such that one of the slataileron control devices operates in an activated command mode when therespective other slat aileron control devices operates in an monitoringmode.
 24. The method according to claim 16, further comprising the stepsof connecting the testing device to one of two separate nose wheelsteering control units provided in the aircraft and operating the twoseparate nose wheel steering control units, synchronously, by using thetesting device such that one of the nose wheel steering control unitsoperates in an activated command mode when the respective other nosewheel steering control unit operates in an monitoring mode.